1. Field of the Invention
The present invention relates to a novel valve stem and valve member arrangement to provide a method of venting a plastic ball valve, and provides a lockout ring which can be used with the ball valve of the present invention as well as with other types of valves.
The vented valve assembly of the present invention includes a valve body having a vent hole therein, and first and second flow-through ends with a valve member receiving chamber thereinbetween, and a stem receiving passage communicating with the chamber. A valve member is disposed within the chamber. The valve member has a throughbore therein in operable alignment with the first end second flow-through ends and at least one valve member vent hole through the wall of the valve member in flow communication with the throughbore. A stem extends through and is rotatably mounted within the stem receiving passage and engageable with the valve member for rotating the valve member in and out of flow-through alignment. A venting means in cooperation with said stem provides selected flow communication with the atmosphere through the valve body vent hole, between the stem and stem receiving passage, through the chamber, and through said valve body vent hole to the flow-through ends.
2. Description of the Prior Art
Typical ball valves utilize a ball as the sealing element which is in alignment with the axis of the stem and free to move axially. Pressure differential across the valve forces the ball in the closed position against the downstream seat and the seat against the body. In fixed ball valves, the ball rotates on stem extensions, with the bearings sealed with O-rings. Plastic seats may be compressed or spring-loaded against the ball and the body by the assembly of the valves, or they may be forced against the ball by pressure across the valve acting against O-rings which seal between the seat and the body.
The Clean Air Act of 1990 limits toxic air pollutants grouped under Title III, and OSHA regulations set forth in 40 CFR 1910 of 1992 lists chemicals that can effect the environment, and/or cause worker's personal injury if they leak or are mishandled. Because of their nature and volume in the process industries, especially in severe service, valves are a major target for controlling emissions. In addition, 40 CFR 1910 calls for various valve lock and interlock systems.
Compliance with these recent OSHA regulations require that during maintenance on a fluid "air" transfer system, the valve must seal the line, vent gases downstream, and be locked out. Assemblies have been devised to successfully accomplish this task using metal ball valves by using a split-body type of ball valve. The ball can be shaped to allow air from the downstream flow to seep between the ball and seat and out of a vent hole in the valve body when the valve is in the closed position. When the valve is in the open position the ball surface effectively closes the valve body vent hole. However, this split body arrangement is limited to use for venting metal ball valves, for the seat must be compressed very tightly between the ball and housing on the upstream side of the valve to prevent leakage. A metal ball in combination with a metal housing and/or metal seat can be used; however, valves having the components made of plastic are susceptible to deformation of the plastic upon tightening the ball against the seat or housing. This limitation limits the use and effectiveness of vented plastic ball valves constructed in the same manner as vented metal ball valves.
The venting means described herein can be used for venting most any type of metal or plastic ball or plug type valve. The plastic ball valve described herein has a dropout type of valve body so that the valve may be removed from a piping system for repair or replacement and provides a good seal using a minimum number of molded parts made of plastic materials, such as polyvinyl chloride and the like.
The vented ball valve of the present invention also utilizes a novel lock-out ring device as a safety device. Various lock-out devices are known in the art. These prior art devices generally are comprised of several parts, mechanically linked together. For instance, one type of lock-out device requires that the lock-out must be slipped onto the valve handle, aligned with respect to the handle and pipe, then squeezed together so that the shackle of a padlock can be insert therethrough. Another type of lock-out device known in the art requires that a pronged device completely encapsulate the valve body and handle, adjusted, aligned, and shackled thereon. Still other lock-out devices consist of a hinged donut type of device which completely enclosed the valve. However, these devices are not particularly suitable for use with the vented ball valve of the present invention, for none of the lock-out devices permit high visibility of valve handle and body, and a low profile which does interfere with the vented stream.
The lock-out rings of the present invention are comprised of a simple one piece design, which are easy to install and inexpensive to manufacture. The "d-shaped" ring is placed coaxially around a pipe and the "leg" member having a hole therein projects outward from the ring body to facilitate alignment with a hole in the handle of the ball valve which accommodates the shackle of a padlock.